KVM: selftests: Make Intel arch events globally available in PMU counters test

Wrap PMU counter test's array of Intel architectrual in a helper function
so that the events can be queried in multiple locations.  Add a comment to
explain the need for a wrapper.

No functional change intended.

Link: https://lore.kernel.org/r/20250117234204.2600624-2-seanjc@google.com


Signed-off-by: Sean Christopherson <seanjc@google.com>